How to make a sharp edge on a mesh
Woah there! that subdivision you did is what is holding you back at the moment.

You'll want to change the edge flow in order to be able to fix the curvature in the way you said.

It should look more like this:


However, there is a way to give this mesh the shape you want, even in its current state.

Step 1: select all the faces that will be starting the edge.

Step 2: hit E, right click and then Alt+S then drag your mouse until you like how it looks, then left click.

Step 3: select the angular edges that you want to get rid of.

Step 4: hit X and select dissolve edges.

Here is an image explaining the process: